The publication of photographs of Prince Harry naked in a Las Vegas hotel room was demonstrably in the public interest, a Conservative member of the Commons culture committee has said.

But the former deputy prime minister Lord Prescott has attacked the Sun for publishing the pictures, saying it proved that self-regulation of the press is dead.

The Sun published the pictures after Prince Charles's aides threatened legal action against newspapers if they published the images, even though they had already been circulated online. One of the two pictures of Harry was splashed across the paper's front page on Friday with the headline: "Heir it is!" In an editorial, the newspaper claimed there was a "clear public interest" in publishing the photographs "in order for the debate around them to be fully informed".

"There is an active reason to publish them [the photos] … There is a clear, demonstrable public interest: the royal family receives money from the civil list; Prince Harry in inviting people to his room [had] the expectation of privacy so there's questions of judgment and questions of security."

She added that Harry could have been subject to a "honey trap", making the issue one of public interest. She also argued that the Leveson media enquiry was cowing the press. "We cannot have a situation where our press as a bloc is so scared of the Leveson enquiry that they refuse to print things in the public interest."

Mensch also said that she was "chilled" after learning that the newspaper industry watchdog body, the Press Complaints Commission, petitioned papers not to publish the pictures. "[The PCC] tried to tread on this story, they should not have done it."

But Prescott told the Guardian: "The Sun's actions prove that as of this morning, self-regulation is now dead. This [story] is not in the public interest, it is in the self-interest of Murdoch to earn money by breaching the privacy of anyone he wants, to sell his newspapers.

"The argument that just because it is all over the internet is spurious at least. There are lots of offensive images and extreme material on the web which international papers don't print."

Prescott added that he had drafted a report on what a new media regulatory framework (pdf), which could replace the PCC, could look like, which he hoped Lord Leveson would consider seriously.

The editor of the Independent, Chris Blackhurst, also speaking on Radio 4's Today programme, said he had taken the view that they were "private photos taken in a private space", that he had not been influenced by Leveson and didn't "need lessons on press freedom and morality from the Sun". He said the argument that publication was in the public interest was spurious.

"As for the idea that it's all out there on the internet and therefore we've got to publish, well I say to that there's a hell of a lot of material out there on the internet freely available to anyone and the press doesn't publish that.

He added, however, that he was concerned that following the Leveson inquiry, the Sunday tabloid press was " not the beast it once was".